The Elsewhere Express by Afterward Samantha Sotto Yambao

"You can't buy a ticket for the Elsewhere Express. Appearing only to those whose lives are adrift, it's a magical train seeming to carry very rare and special cargo: a sense of purpose, peace, and belonging. Raya is one of those lost souls. She had dreamed of being a songwriter, but when her brother died, she gave up on her dream and started living his instead. One day on the subway, as her thoughts wander, she's swept off to the Elsewhere Express. There she meets Q, an intriguing artist who, like her, has lost his place in the world. Together they find a train full of wonders, from a boarding car that's also a meadow to a dining car where passengers can picnic on lily pads to a bar where jellyfish and whales swim through pink clouds"--